Surgical anchors are used instead of surgical suturing, which is often both time consuming and inconvenient, in order to join two tissue locations. A surgeon can often use a stapling apparatus to implant an anchor into a body tissue and thus accomplish in a few seconds, what would take a much longer time to suture. A surgical anchor is used, for example in inguinal hernia surgery to fasten polypropylene mesh to the abdominal wall in order to reinforce the abdominal wall.
Conventional surgical fasteners have been in the form of ordinary metal staples, which are bent by the delivery apparatus to join together body tissues. These staples comprise a pair of legs or prongs joined together at one end by a crown that may be straight or arcuate. During deployment of the staple, the prongs are inserted into a tissue and are then made to bend inwards towards.
At present, there are a variety of surgical fasteners and fastening devices available for endoscopic or open procedures, to attach tissues together, or to attach a mesh patch to a tissue. One such surgical fastener is a surgical stapler, or clip applicator. In this stapler, a plurality or stack of unformed staples are contained within a cartridge and are sequentially advanced or fed within the instrument by a spring mechanism. A secondary feeding mechanism is employed to separate the distal most staple from the stack, and to feed the distal most stapler into the staple closing mechanism. Such mechanisms are found in U.S. Pat. Nos. 5,470,010, and 5,582,616.
In some applications, the body tissue is accessible from two opposite direction so that an anvil may be used to deform the legs of a staple after having passed through the body tissue. In applications where access to the tissue is from only one direction, an anvil may be used to deform the crown of a conventional staple so that the legs project towards each other in the body tissue so as to hold the staple in the tissue.
Another stapler mechanism, used mostly for mesh attachment to tissue does not use an anvil. Instead, a fastener comprising a helical wire is screwed or rotated into a tissue, in order to join tissues to affix a polypropylene or similar material mesh or other patch to the tissue together. Instruments and fasteners of this type are found in U.S. Pat. Nos. 5,582,616, 5,810,882, and 5,830,221. Another type of fastener that does not need an anvil applies fasteners made from a shape memory alloy such as Nitinol™. These fasteners are mainly used to fasten prosthetic material or artificial mesh to tissue.
These fasteners and fastening devices suffer from significant drawbacks especially when attaching fasteners to soft tissue. The strength of attachment of these devices depends mainly on the content and size of collagen fibers. Most soft tissue, such as subcutaneous tissue and fatty tissue surrounding internal organs, has few and slender collagen fibers and hence the attachment of the common art fasteners to such tissue is weaker than attachment to stronger tissues such as fascia or ligaments, which have more and larger collagen fibers.